1. Field of the Invention
The invention relates to mast mounted outdoor lighting systems for illuminating roadways, sidewalks, parking lots or the like, and specifically to an improved mast mounted lighting system wherein a watertight casing containing power distribution components is stored within the mast foundation and is accessible by the user through the base of the mast.
2. The Prior Art
Outdoor mast lighting systems are well known in the prior art. Such systems commonly are supported above the surface to be lighted by a long pole or mast. Masts are typically hollow, and may be round, square or of any selected cross-sectional shape which provides adequate stability. The mast may include a breakaway base at its lower end having an opening (or "handhole") therein, through which the interior of the mast may be accessed by maintenance or installation personnel. The mast is mounted on a foundation of concrete or other suitable material set permanently into the ground and may be affixed to the foundation by a plurality of anchor bolts set into the foundation, which engage corresponding holes in the breakaway base.
Suspended at the top of the mast is an electrical component, commonly an electric light. In some applications, a cantilevered secondary mast supports the light over a street or sidewalk. In other applications, a ring of high-intensity lamps may be supported radially around the distal end of the mast. The electrical component is electrically connected to a power source, generally in series with a plurality of other commonly powered mast units in a given area.
Power delivery to each mast unit in a commonly powered system has been accomplished in a variety of ways in the prior art. In one such system, the output of a master circuit breaker may be connected to an electric power cable which runs to the base of the mast unit. The power cable connects to a fuse and surge arrestor assembly disposed within the hollow mast, which prevent current surges caused by lightning, voltage spikes or other anomalies from damaging the light fixture or the master circuit breaker. Access to the fuse and surge arrestor assembly is commonly provided by locating that assembly adjacent a handhole in the mast.
The performance of such a system is impaired by several shortcomings. Wire and cable attachments are generally made by splices, which are vulnerable to failure when tensile forces are applied to the connections. Because of the vertical orientation of the cable sections, gravitational forces are exerted at all times on the spliced connections which may tend to come apart. In catastrophic failure, such as that caused by a collision by an automobile or truck, the spliced connections are likely to disconnect, causing an interruption in service throughout the grid, and exposing dangerously "hot" wires.
In another prior art system, the fuse and surge arrestor assembly is located in a remote underground manhole. Such a system requires significantly greater expense and space to install, as a remote hole must be dug and maintained for each lighting unit within the grid, and additional cable is required to accommodate the remotely located electrical components.